An embodiment relates generally to embodiment relates generally to rechargeable battery systems in a vehicle.
Electronic portable devices such as cell phones are powered by battery packs that require recharging. While it is known that such portable devices utilize contact terminals for transferring electrical energy between an external power source (e.g., power outlet) and the electronic portable device, contactless charging uses inductive charging to recharge portable devices without the electrically coupling contact terminals to transfer the electrical energy to the electrical portable device. Examples of such portable devices include cordless telephones, electronic toothbrushes, and other electronic convenience devices. An inductive charging system typically includes a base charging unit that includes an inductive coil for generating an electromagnetic field. An electrical charge is induced in an inductive coil in the electrical portable device by the inductive coil of the base charging unit. The induced electrical charge is converted to a DC voltage for recharging the battery.
Electrical devices such as cell phones have a self-protection mode where the device enters a safe charging mode if the temperature of the cell phone becomes greater than a predetermined temperature. The safe charging mode involves allowing only a trickle charge of electrical energy charge the battery. This prevents damage to the battery as well as the electronic components with the cell phone. Typically ambient temperature of an environment, such as a room of a house or building, will not cause the cell phone to enter a safe charging mode; however, charging environments such as vehicle have higher ambient temperatures, particularly if the vehicle is exposed to the sun. In such an environment, the cabin temperature can vary from 70 C to −20 C. This condition along with the heat generation of the primary base station may cause the cell phone battery temperature to increase above the predetermined temperature threshold and enter the safe charging mode. The inability of the cell phone to charge at the expected rate is a nuisance to the user and inconvenience to the user.